In DSpace 5, each "Context" established a new DB connection. Context then committed or aborted the connection after it was done (based on results of that request). Context could also be shared between methods if a single transaction needed to perform actions across multiple methods.

In DSpace 6, Hibernate manages the DB connection pool. Each thread grabs a Connection from the pool. This means two Context objects could use the same Connection (if they are in the same thread). In other words, code can no longer assume each new Context() is treated as a new database transaction.

This is what we saw in DS-3659, two separate Context objects used the same connection, and one accidentally rolled back the changes of a previous Context (because they were in the same thread).